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Sunday, December 11, 2016

Is There A Science to Physical Therapy?

Many
disciplines rely on a grand theory, or an overarching conceptual
framework -- something that ties all the pieces together. According to Carter
and Lubinsky,1 a grand theory provides
a “broad conceptualization of phenomena.” In other words, a grand theory
purports to address big ideas -- or even an entire discipline -- with one
theoretical context. It attempts to subsume the middle-range theories within a
discipline, which typically apply more to direct action or clinical practice. For
example, physics has a number of competing grand theories: The Grand Unified
Theory, The Theory of Everything, and String Theory. (They say competition is
good for business.) When it comes to healthcare professions, occupational
therapy and nursing have both given considerable thought to theory over the
last several decades.1–3 What about physical
therapy? Does it have a grand theory?

In 1975 Dr.
Helen Hislop delivered a pivotal address titled The Not-So-Impossible Dream
concerning the state of the physical therapy profession.4 In the lecture and
corresponding paper, Hislop declared physical therapy to be in the midst of a
crisis. Physical therapists knew not their identity nor their purpose. They
defined themselves by their specialties or treatment methods rather than core
scientific principles. They were hard-pressed to differentiate themselves from
other movement professionals. Due to a lack of scientific know-how, their
methods were often outdated and lacked scientific rigor. She warned her
colleagues that the physical therapy profession would be destined for failure
if they could not identify a unified purpose -- a purpose “borne in science.”

Dr. Helen Hislop [4]

To avoid
impending professional doom, Hislop proposed the grand theory of pathokinesiology.
She defined pathokinesiology as the application of anatomy and physiology to
abnormal human movement. Within the pathokinesiology framework, Hislop
described an interweaving hierarchy of the human organism ranging from cells to
tissues, organs, systems, person, and lastly, family. The primary goal of
physical therapy, Hislop asserted, was to restore movement homeostasis at the
tissue, organ, system, and person levels. This restoration would be accomplished
primarily through therapeutic exercise. Pathokinesiology was the
“distinguishing clinical science of physical therapy,” Hislop proclaimed. She
urged her fellow physical therapists to adopt the pathokinesiology framework
for the diagnosis, treatment, and prevention of movement disorders.

Hierarchy of the human organism [4]

To make this
ideology more concrete, consider a patient who presents with a hamstring
strain. This perturbation would have occurred at the tissue level of the
pathokinesiology hierarchy. Disruptions at higher levels would likely accompany
the strain. There might be stress at the organ level, weakness and decreased
range of motion at the system level, and reduced mobility at the person level.
Therapeutically, the physical therapist could intervene with manual therapy (on
the tissues), passive stretching (to the muscle-tendon system), and
strengthening exercises (for the person).

In this
context, pathokinesiology appears to be an attractive model. Rather than
fixating on particular treatment techniques, pathokinesiology contextualizes
patient care in terms of the aforementioned unified goal: movement homeostasis.
Whichever therapies best accomplish the goal for the individual patient are the
ones that should be used. Thus, rather than marry themselves to specific
techniques, physical therapists must become devoted to scientific principles.
Techniques are constantly changing, but principles endure. As consumers of the
scientific literature, pathokinesiology-based practitioners can seamlessly
integrate or abandon modalities as research discovers or debunks them.

Indeed, Hislop
made a compelling case for pathokinesiology as the grand theory of physical
therapy. As history would go on to indicate, she was far ahead of her time. Nonetheless,
over the next decade and beyond, pathokinesiology became little more than a
buzzword, never truly taking root.5 In 1986 the American
Physical Therapy Association attempted to rekindle this critical discussion by
holding a symposium on the issue. In the follow-up papers published in the
Physical Therapy Journal, the authors expressed varying degrees of support and
distaste for Hislop’s theory.5–11 Walker, for one,
illustrated how The University of Southern California adopted Hislop’s theory
and had been conducting impactful research in pathokinesiology.11 While others were less
enthused with pathokinesiology, most did acknowledge the continued need for a
collective professional identity. However, Hislop’s simple proclamation that
pathokinesiology was that identity didn’t automatically make it so.8

The theory of
pathokinesiology has several shortcomings. One of the primary arguments against
it is the preexistence of other well-established sciences like anatomy,
physiology, biomechanics, and pathology. It’s unclear where pathokinesiology as
a science can fit in given existing research paradigms and terminology in these
fields.7,9 Regarding this point,
to this day there is still no “Journal of Pathokinesiology.” In addition, most
present-day clinicians continue to use verbiage like “pathoanatomy” and “pathophysiology”
instead. Nor is Hislop’s definition of pathokinesiology entirely applicable to the
many and diverse branches of physical therapy. For instance, one
cardiopulmonary physical therapist noted a major disconnect in the literature
of her specialty to normal and abnormal movement.7 This connection was
Hislop’s most fundamental proposition.

Hislop's pyramidal structure of physical therapy [4]

Another major
flaw of pathokinesiology is the placement of therapeutic exercise at its
pinnacle. The practice of physical therapy -- and all its various specialties -- involves much more than therapeutic exercise.12 In addition to the
biomechanical factors associated with rehabilitation, there are also
psychological and social ones that can be equally important. Hislop did well to
acknowledge the importance of treating patients’ psychology in her address. However,
by excluding movement interventions beyond the person level, she relegated the
social component to outside of the physical therapist’s scope. Moreover, by
solely dealing with therapeutic exercise, she diminished the physical
therapist’s role in injury prevention.

Perhaps the
best evidence of all that pathokinesiology never came to be regarded as
physical therapy’s grand theory came in 1995. A group of Canadian physical
therapists issued sentiments that eerily echoed those of Hislop twenty years prior.13 They declared once
again that physical therapy was facing an identity crisis. To avoid impending
professional doom, they introduced the Movement Continuum Theory. Not by
coincidence, the Movement Continuum Theory held many of the same basic tenets
as pathokinesiology. Chiefly, the authors defended the already familiar notions
from pathokinesiology that (1) “movement is essential to life,” (2) “movement
occurs on a continuum from the microscopic level to the level of the individual
in society,” (3) “movement levels on the continuum are influenced by physical,
psychological, social and environmental factors,” and (4) “movement levels on
the continuum are interdependent.”13 Within this framework,
the authors expanded on Hislop’s hierarchy of the human organism. They included
additional levels in the hierarchy and accounted for both intrinsic and
extrinsic factors to the person. Most importantly, they stressed that physical
therapists can act on any and all levels of the continuum to improve movement
capacity.

The Movement Continuum Theory [13]

Another key
addition to this model was the distinction between a patient’s “current
movement capacity,” “preferred movement capacity,” and “maximum achievable
movement potential.”13 To illustrate these
principles, recall the earlier example of the patient with the hamstring strain
injury. Suppose that patient is a collegiate field hockey player. Based on a
variety of parameters like age, genetics, and anthropometry, she has a certain maximum achievable movement potential.
This is her theoretical ceiling for movement capacity. She also has a preferred
movement capacity, or desired level of movement. Given her primary activity
(field hockey), that preferred capacity may be fairly close to her maximum
achievable.

At the time of
the injury, this athlete would have been operating at some current movement
capacity, likely situated below both her preferred and maximum capacities. When
the patient presents in the clinic a few weeks post-injury, her preferred
movement capacity is unchanged, but her current movement capacity has dropped
significantly below pre-injury level. Thus, there now exists a differential
between her current and preferred movement capacities. The developers of the
Movement Continuum Theory identified the reduction of this differential as the
physical therapist’s primary purpose.13 To borrow Hislop’s
words, this was the physical therapist’s identity.

By closing
another gap -- that between the current and maximum achievable movement
potential -- the physical therapist’s role in injury prevention also meshes with
the Movement Continuum framework. While treating the injury, the therapist can
address areas of movement dysfunction unrelated to the injury and its sequelae,
too. In contrast to pathokinesiology, Dr. Shirley Sahrmann refers to this
treatment model as kinesiopathology in her perspective paper The
Human Movement System: Our Professional Identity.14 In addition to treating
movement dysfunction resulting from pathology (i.e. pathokinesiology),
physical therapists must work to prevent movement dysfunction from resulting
in future pathology (i.e. kinesiopathology). In the example of the field
hockey player, that might mean bilateral strengthening of the glutei to
alleviate the burden on the hamstrings in hip extension.

At first pass,
the idea of a grand theory of physical therapy may seem to be just a matter of
semantics. It certainly did to me. As long as patient outcomes are positive,
who cares what the science is called? Upon further investigation, however, it becomes
clear that a grand theory is directly linked with those same patient outcomes.
Identifying the scientific framework of physical therapy provides the
discipline with a body of knowledge they can take ownership of. It unifies the
various specialty disciplines as one. It intimately links clinicians with
researchers and lends to treatment methods being subjected to increased
scientific scrutiny. All of these factors no doubt result in better and more precise
patient care. Above all, a grand theory ensures the long-term survival of the
physical therapy profession.

There’s no
denying that pathokinesiology had a number of imperfections which prevented its
widespread adoption. Nevertheless, it did lay the groundwork for future models,
which may in time prove more complete. More than anything, Hislop’s mission was
to promote a dialogue regarding the essence of physical therapy and its
relationship with science. As evidenced by pathokinesiology’s successors, the
Movement Continuum Theory and Sahrmann’s Human Movement System, this discourse
has resurfaced again and again. Although pathokinesiology was never accepted as
the grand theory of physical therapy, in this sense Hislop’s Not-So-Impossible
Dream may just have been realized after all.